Method for the minimization of the effects of pulsations in intermittent pumping systems

ABSTRACT

New and improved method for minimizing the effects of pulsations which occur during the operation of intermittent pumping systems is provided and, as disclosed, is applied to a peristaltic pump which is utilized in a fluid sample supply, treatment and analysis system and comprises the minimization of the effects of the pulsation which occurs each time a pump roller occludes the compressible pump tube, and the minimization of the effects of the pulsation which occurs each time a pump roller discontinues the occlusion of the compressible pump tube.

United States Patent [72] Inventors Jack lsreeli Mnrnaroneclr; AaronKassel, Brooklyn; Robert Dannewltz, Yonkers, all of N.Y.

Appl. No. 71,777

Filed Sept. 14, 1970 Patented Dec. 21, 1971 Assignee TechniconCorporation Tarrytown, N.Y.

METHOD FOR THE MINIMIZATION OF THE EFFECTS OF PULSATIONS IN INTERMITTENTPUMPING SYSTEMS 25 Claims, 5 Drawing Figs.

11.8. C1. 417/53, 417/476 Int. Cl ..F04b 43/12, F04b 45/08 FieldolSearch 417/53, 54, 474, 475, 476, 477

[56] References Cited UNITED STATES PATENTS 3,134,263 5/1964 De .Iong71/423 3,588,281 6/1971 lsreeli et a]. 417/53 Primary Examiner-CarltonR. Croyle Assistant Examiner-Richard E. Gluck Attorney-S. P. TedescoABSTRACT: New and improved method for minimizing the effects ofpulsations which occur during the operation of intermittent pumpingsystems is provided and, as disclosed, is applied to a peristaltic pumpwhich is utilized in a fluid sample supply, treatment and analysissystem and comprises the minimization of the effects of the pulsationwhich occurs each time a pump roller occludes the compressible pumptube, and the minimization of the effects of the pulsation which occurseach time a pump roller discontinues the occlusion of the compressiblepump tube.

64 s2 so 62 A2.AIS1ASI+RA SAMPLE SUPPLY DEVICE PATENIEU UEEZI Em SHEET 1OF 3 n: fr #1 2 Fig/l 635$? I mm INVENTORS JACK ISREELI AARQN KASSEL Y RBERT ANNEWITZ o I} ATTORNEY PATENTEU IE2! B?! SHEET 3 0F 3 RECORDEDRESULT OF INTEREST RECORDED RESULT OF INTEREST TIME RECORDED RESULT OFINTEREST FIG.

32 (A)s2(A)s2(A)s2(A) SI 5 FIG. 5

INVENTORS w. m 0 a T I N T 5 M .A TMMD AV S IW E M WAR Y B METHOD FORTHE MINIMIZA'IION OF THE EFFECTS OF PULSATIONS IN INTERMI'I'IENT PUMPINGSYSTEMS BACKGROUND OF THE INVENTION 1. Field of the Invention Thisinvention relates to new and improved method for minimizing the effectsof pulsations which occur during the operation of intermittent pumpingsystems.

2. Description of the Prior Art In any intermittent pumping system inthe nature, for example, of a peristaltic pumping system or apressure-pumped exchange valve and pilot fluid pumping system, it may beunderstood that intermittent pulsations in the provided flow rate will,of necessity, occur. For use, for example, in automatic, sequentiallyoperable substantially constant flow rate fluid sample supply, treatmentand analysis means of the nature disclosed in U.S. Pat. No. 3,241,432issued Mar. 22, 1966 and assigned to the assignee hereof, and which areoperable to supply, treat and analyze a stream consisting of successivesample portions, it may be understood that such intermittent pumpingsystems may be utilized without significant regard for such pulsationsbecause of the minimization of the effects of the latter as provided bythe relatively long sample portion sampling times and the relativelyhigh flow rates and volumes of said sample portions, which, in essence,combine to function to average or spread out such effects overrelatively long periods of time and throughout relatively large sampleportion volumes to thereby render the same tolerable. For use of suchintermittent pumping systems with newly developed and highly improvedversions of such sample supply, treatment and analysis means which areoperable, to significant advantage, at substantially reduced sampleportion sampling times and with substantially reduced sample portionflow rates and volumes, however, it may be understood that a method mustbe provided to minimize the efiects of such pulsations, or thatunacceptable variations in the essential sample portion phasing and inthe essential sample portion-sample treatment fluid proportioning willresult.

OBJECTS or THE INVENTION It is, accordingly, an object of this inventionto provide new and improved method to minimize the effects of pulsationswhich occur during the operation of intermittent pumping systems.

Another object of this invention is to provide method as above which maybe applied to said intermittent pumping systems without structuralmodification of the latter.

A further object of this invention is the provision of method as abovewhich is particularly adaptable for use in intermittent pumping systemswhich form part of automatically operable, substantially constant flowrate fluid sample supply, treatment and analysis means.

SUMMARY OF THE INVENTION As specifically disclosed herein by way ofillustration, the method of the invention is applied to a peristalticpump which is operable, in a fluid sample analysis system, through theprogressive occlusion of a compressible pump tube by a plurality ofsubstantially equally spaced pump rollers to pump fluid sample portionsin a precisely phased successive stream thereof from fluid sample supplymeans to fluid sample treatment and analysis means. A separating fluidportion which includes an air segment is provided in said fluid sampleportion stream intermediate adjacent fluid sample portions. A pulsationin the pump delivery rate occurs each time a said pump roller occludessaid pump tube, and each time a said pump roller discontinues theocclusion of said pump tube. Said fluid sample portions are supplied tosaid compressible pump tube by the aspiration thereof from samplecontainer means through the inlet end of a connected sample offtakedevice which functions as pump inlet means, and each of said fluidsample portions is treated downstream of said compressible tube pump bythe mixture thereof in precisely determined proportion with a sampletreatment fluid through the merger of a stream of the latter with saidsample portion stream. The method of the invention minimizes the effectsof the first-mentioned pulsation by insuring, through proper control ofthe operational timing of said pump rollers and said pump inlet meansflow path length determination, that said offtake device inlet end isnot exposed to the air at the time said pulsation arrives thereat tothus insure the aspiration of the separating fluid portion air segmentof the required volume. The method of the invention minimizes theeffects of the second-mentioned pulsation by insuring, through properdetermination of the flow path length between said pump roller as thelatter discontinues said occluding contact, and the point at which saidsample portion stream merges with said sample treatment fluid stream,that one of said separating fluid portion air segments is disposed atsaid merger point at the time of the arrival thereat of said pulsationto thus minimize the extent of the change, if any caused thereby in saidsample portion-sample treatment fluid proportion and, in any event,restrict the same to the beginning or end part of each of said sampleportions to render the same incapable of modifying the recorded sampleportion analysis results.

DESCRIPTION OF THE DRAWINGS The above and other'objects of he inventionare believed made clear by the following detailed description thereoftaken in conjunction with the accompanying drawings wherein:

FIG. 1 is a flow diagram illustrating the application of the method ofthe invention to the operation of peristaltic pump means in a fluidsample supply, treatment and analysis system, and depicts said pumpmeans in a first operational position thereof;

FIG. 2 is a flow diagram depicting the peristaltic pump of FIG. 1 in asecond operational position thereof;

FIG. 3 is a graph depicting pump delivery plotted against time andillustrates the pump pulsations of interest;

FIG. 4 is a graph depicting treated sample portion optical densityplotted against time and illustrates the minimization of the effects ofone of the pulsations of FIG. 3; and

FIG. 5 is a flow diagram illustrating fluid flow through the peristalticpump of FIG. 1 when the same is used in a somewhat differently operablefluid sample supply, treatment and analysis system.

DETAILED DESCRIPTION OF THE INVENTION Referring now to FIG. I, new andimproved sample supply system constructed and .operative in accordancewith the teachings of this invention are indicated generally at 8, andcomprise compressible tube pump means as indicated generally at 10 andoperatively associated sample supply means as indicated generally at 12.

The sample supply means 12 may, for example, take the form of thoseshown and described in U.S. Pat. No. 3,134,263 issued May 26, 1964 toEdward B. M. DeJong, and comprise a turntable 14 upon which is disposeda generally circular array of sample containers 16. A sample offtakedevice is indicated generally at 18 and comprises a sample offtake tube20 and offtake tube operating-means 22, respectively. A wash liquidreceptacle 24 is disposed as shown adjacent the turntable 14, whilesample supply device drive means are indicated at 26 and are operativeto drive each of the turntable l4 and the sample offtake device 18 asindicated by the dashed lines extending therebetween.

In operation, the turntable 14 is intermittently rotated, or indexed, topresent each of the sample containers 16 in turn to the sample offtakedevice 18, while the latter is operated to immerse the inlet end orofftake tube 20 in a thusly presented sample container for apredetermined period of time to aspirate (as described in detailhereinbelow) a measured volume of the sample therefrom, to then transferthe said offtake tube inlet end through the ambient air for immersion inthe wash liquid receptacle for a predetermined period of time to thusaspirate a measured volume of ambient air followed by a measured volumeof said wash liquid, and to then again transfer the said offtake tubeinlet and through the ambient air for immersion in the next-presentedsample container 16 for a predetermined period of time to thus aspirateaNother measured volume of ambient air and commence the aspiration of ameasured volume of the sample from said next-presented sample container.

As a result, it may be understood that a stream S consisting ofsuccessive ones of portions of said samples of substantially equalpredetermined volume as spaced, in each instance, by a segment of air A,a segment of wash liquid W and a segment of air A, respectively, will besupplied to the offtake tube 20.

The compressible tube or peristaltic pump may, for example, take thegeneral form of that shown and described in U.S. Pat. No. 3,227,091issued Jan. 4, 1966 to Jack lsl'eeli et al., and comprises spaced pumptube mounting blocks as indicated at 32 and 34.

A compressible pump tube 36, which is made from any suitably resilientmaterial of appropriate strength characteristics in the nature, forexample, of silicone rubber, is extended as shown between the said pumptube mounting blocks and affixed thereto by means of the placement ofsaid pump tube in nonillustrated aligned mounting grooves formed in saidpump tube mounting blocks, and the attachment of collar elements 38 and40, as shown to opposite end portions of said pump tube, all in a mannermade clear in said U.S. Pat. No. 3,2 27,091. The inlet end of thecompressible pump tube 36 is connected as indicated at 41 to the outletend of the sample ofitake tube 20.

A pump roller assembly is indicated generally at 42 and comprises anendless chain 44 which is disposed as shown around a chain guide member46 and is driveable therearound in the indicated clockwise directionthrough the driven rotation of a chain drive sprocket 48.

A plurality of substantially equally spaced pump rollers 50A, 50B, 50Cand 50D are rotatably mounted in any convenient manner on endless chain44 as shown, whereby may be understood that those of said rollers whichare, at any given point in time, mounted on the upper throw of theendless chain 44 will be movable with the latter in the direction fromleft to right as seen in FIG. 1. Although for simplicity of illustrationonly one chain and drive sprocket are depicted, it may be understoodthat at least two of the same would be provided in spaced, generalalignment, and that the respective pump rollers would, of course, extendtherebetween.

A pump platen is indicated at 52 and may be understood to be movable, asby pivotal movement, from a nonillustrated open" position thereof to thedepicted closed" position thereof wherein the pump tube 36 will bedisposed as shown in firm contact with the undersurface of said platen,and will be forced to conform with the configuration of the bottomsurface 54 of said groove and pressed thereby against the respectiverelevant rollers 50, all again as described in detail in said U.S. Pat.No. 3,227,091.

Pump drive means, which may, for example, take the form of any suitableelectric motor, are indicated at 56, and are operatively connected, asindicated by the dashed line, to the chain drive sprocket 48 todrivingly rotate the latter. In addition, and for reasons described indetail hereinbelow, the operation of sample supply device drive means 26is synchronized with the operation of the pump drive means 56, and thismay be understood to be indicated in the drawings by the extension oflead 58 therebetween. Alternatively, it is believed clear that a singledrive means in the nature of a suitable electric drive motor may beprovided and operatively connected, as by conventional mechanicalconnecting means, to both the pump 10 and the sample supply device 12 todrive the same in the described synchronized manner.

With the respective pump components arranged and operative as described,it may be understood that driven, clockwise rotation of the chain drivesprocket 48 will effect movement of the rollers 50 affixed to the upperthrow of endless chain 44 from left to right as men in FIG. 1 with theresult that the compressible pump tube 36 will be progressivelycompressed or occluded thereby in said direction to in turn pump fluidstherethrough. Accordingly, may be understood that the successive samplestream 8 will be supplied as indicated from the compressible pump tube36 to a sample stream supply conduit 62, which is connected to theformer as shown at 64, for supply through said sample supply conduit asindicated to the nonillustrated sample treatment and analysis means. Inaddition, it is reiterated that the sample portions which constitutethis sample portion stream will be spaced, each from the other, by aseparating fluid portion which, in this instance, will be constituted asdescribed by a segment of air A1, a slug of wash liquid W, and a segmentof air A2, arranged in that order.

Sample treatment fluid supply means are indicated generally at 66 andmay be understood to function to supply a sample treatment fluid to thesample portion stream supply conduit 62 for mixture therewithin incarefully predetermined proportion with each of said sample portionsbeing pumped therethrougli.

The sample treatment fluid supply means 66 may, for example, take thegeneral form of those shown and described in the copending applicationfor U.S. Pat. Ser. No. 120,153 of Edward B. M. DeJong filed Mar. 2, 1971and assigned to the assignee hereof (continuation in part of U.S. Pat.Ser. No. 712,431 filed Mar. 12, 1968, now abandoned) and, as such, willcomprise a tank 68 of air at suitable pressure, as, for example, 2,200psi. connected as shown by conduit 70 through suitable pressureregulator means 72 to a T-fitting 74 to maintain the latter atsubstantially constant pressure in the order, for example, of 66.8 cm.Hg. For use in applications wherein the respective samples areconstituted by blood serum samples from different patients, the sampletreatment fluid of interest may, for example, be constituted by acolor-producing reagent liquid which, when mixed with said sampleportions, will enable the respective colorimetric quantitative analysesthereof with respect to a predetermined blood sample constituent, all asdescribed in greater detail in said U.S. Pat. No. 3,241,432.

A conduit 78 extends as shown from outlet of the Tfitting 74 through thescrew-on cover 80 of a reagent liquid flask 82 to thus pressurize theinterior of the latter at said substantially constant pressure. Anoutlet conduit 84 connects the interior of the flask 82 to the inlet ofa precisely calibrated high flow resistance coil 86, the outlet of whichis in turn connected as shown by reagent liquid supply conduit 88 to oneinlet of a T- fitting 90 which is interposed in the sample portionstream supply conduit 62.

The other outlet of the T-fitting 74 is connected as shown by conduit 92to the inlet of a precisely calibrated high flow resistance coil 94, andthe outlet of the latter is connected by air supply conduit 96 to aT-fitting 98 which is interposed as shown in the reagent liquid supplyconduit 88.

For use as described in greater detail hereinbelow in automaticallyoperable, blood serum sample treatment and analysis means, the high flowresistance coil 86 will preferably be disposed in a temperature controlbath as indicated in dashed lines at 99 to maintain the temperaturethereof at a suitable, substantially constant level as, for example, 37C. to in turn maintain the temperature, and accordingly the viscosityand flow rate of the reagent liquid flowing therethrough atsubstantially constant, predetermined values. If necessary, and/ordesired, the respective reagent liquid flask 82 and portions at least ofthe respective conduits 84 and 88 may also be immersed in saidtemperature control bath.

By this arrangement is believed made clear that the pressurized air fromtank 68 will be effective to pump the reagent liquid R from the flask 82at a substantially constant, predetermined flow rate through the highflow resistance coil 86 and therefrom, through reagent liquid supplyconduit 88, to the sample stream supply conduit 62 for mergertherewithin with the sample portion stream S flowing through the latter.Concomitantly, it may be understood that the pressurized air from tank68 will be flowed, again at substantially constant, predetermined flowrate, through high flow resistance coil 94 and therefrom through airsupply conduit 96 for merger with the reagent liquid stream flowing inreagent supply conduit 88 to air segment the same as shown to promoteproper mixing thereof with the sample stream S upon the merger thereofas discussed hereinabove.

Although compressible tube proportioning pumps in the nature of the pumphave, to date, proven preferable for use in automatically operable,substantially constant flow rate sample treatment and analysis means ofthe nature disclosed in said US. Pat. No. 3,24l,432, it may beunderstood that there is one operational characteristic of said pumpswhich must be taken in consideration for such use, and especially whenapplied to improved versions of said sample treatment and analysis meanswhich are operable at substantially reduced sample volumes andsubstantially increased sample analysis rates. More specifically, and asseen in FIG. 3 wherein the graph 100 represents proportioning pumpdelivery as plotted against time for the travel of one of thecompressible pump rollers 50 through one tube compressing cycle thereof,it may be understood that pulsations as indicated at 102 and 104 willrespectively occur in said pump delivery rate as the said pump rollermakes contact with and occludes the pump tube 36 at the commencement ofthe pumping cycle of interest, and as the said pump roller terminatesthe occluding contact thereof.

with said compressible pump tube at the termination of said pumpingcycle.

Sample treatment and analysis means of the nature discussed may beunderstood to be satisfactorily operable only at substantially constantflow rate, and to further depend for satisfactory constant flow rate,and to precise proportioning between each of the sample portions and thereagent liquid which is merged therewith, and upon the substantiallyprecise maintenance of a predetermined phase relationship between therespective sample portions. Accordingly, it becomes essential that theeffects of pulsations as indicated at 102 and 104 in FIG. 3 upon suchflow rate, proportioning and sample portion phase. relationship beminimized, if not altogether removed.

Considering first the pulsation 102 which occurs as set forthhereinabove as a pump roller commences the occlusion of the compressiblepump tube 36, it may be understood that this point in the operation ofthe compressible tube pump 10 as illustrated in FIG. 1 wherein the pumproller 50B is depicted as commencing the occlusion of the compressiblepump tube 36. At this occurs, it may be understood that the pulsation102 of FIG. 3 will, of course, travel in both directions from the pointof roller-pump tube contact through the sample portion stream S thenflowing in said pump tube. The travel of this pulsation in the directionfrom left to right as seen in FIG. 1, or, that is to say, the downstreamdirection, will be terminated at the roller 50A since the latter is, atthis point in time, fully occluding the compressible pump tube 36 tothereby render substantially impossible further travel of said pulsationin this direction.

The travel of this pulsation in the direction from right to left as seenin FIG. 1 or, that is to say, the upstream direction will, however, beunrestricted to and through the inlet end of the sample offtake tube 20.As a result, it may be understood that the said offtake tube, theturntable l4 and the compressible pump tube 10 are arranged inaccordance with the teachings of this invention, as through carefulpredetermination and control of the operational timing of the respectivesample supply device drive means 26 and the pump drive means 56, toinsure that the said offtake tube inlet end is not exposed to theambient air at the time that the pulsation 102 reaches the said offtaketube inlet end. More specifically, and bearing in mind the substantialimportance of proper phasing of the respective sample portions which arepumped through the compressible pump tube 36, and the obviouslyessential function of the respective air segments A of predetermineduniform volume in maintaining such phasing and, in conjunction with theslug of wash liquid W, in providing for intersample portion cleansing toinhibit the contamination of a succeeding sample portion by the residueof a preceding sample portion, it is believed clear that if the inletend of the offtake tube 20 is exposed to the ambient air at the time thesaid pulsation arrives thereat, the effect of the latter will, ofcourse, be to substantially reduce, if not eliminate, the amount of airwhich is at that time aspirated to form an air segment A.

If the amount of airaspirated is simply reduced but is still adequate toform aleading air segment as indicated at A1 in FIG. 1 of at least theminimum volume required to occlude the nonuniform tube 36, it may beunderstood that the said air segment Al will be smaller than and thus ofnonuniform volume with regard to the trailing' air segment as indicatedat A2 whereby the essential sample portion phase relationship may bemodified to obvious disadvantage. If, on the other hand, the amount ofair aspirated is reduced to the extent that insufficient air is providedfor the formation of an air segment A of minimum volume to fully occludethe pump tube 36- thereby resulting only in the formation of a suspendedair bubbleor if no air is aspirated at all, it is believed. clear thatthe essential inter sample portion cleansing and sample portionseparating functions of the air segment A which was to have been formedwill also be eliminated along with the phase relationship destruction asdiscussed hereinabove.

To better illustrate this, if it is assumed, for example, that a totalof 12 seconds are available for the aspiration of each of the sampleportions and the separating fluid portion which is constituted by therespective air segments A and slug of wash liquid W which precede thesame, that only 1.5 of these l2 seconds are available for the aspirationof said air segments and wash liquid slug, that the pulsation 102 is of1 second duration, and that the sample supply system 8 is arranged tooperate to aspirate air to form segments A of the minimum volumerequired to occlude the compressible pump tube 36, it is believed clearthat the arrival of the pulsation 102 at the inlet end of offtake tube20 during that portion of the 1.5 seconds air-wash liquid aspirationtime in which air is being aspirated will, in all probability, result inthe aspiration of an air volume, if any, which isinsufiicient to occludethe compressible pump tube 36 to obviously unacceptable effect asdiscussed in detail directly hereinabove.

Preferably, the sample offtake tube 20 will be arranged as illustratedso that the inlet end thereof will be immersed in a sample container 16generally intermediate the aspiration of a sample portion at the time ofthe arrival of the pulsation 102 at said inlet end, with resultantsubstantial absorption of said pulsation to render the efiects of thelatter substantially undetectable during the steady state flow rateportion of sample stream flow.

Alternatively, the sample offtake tube 20 may be arranged so that theinlet end thereof will be immersed in the wash liquid receptacle 24 atthe time of arrival of the pulsation 102 thereat although this may, ofcourse, prove unacceptable in instances as discussed hereinabove whereinthe total time for wash liquid slug aspiration is so short in relationto the duration of the pulsation 102 that the former cannot accommodatethe latter and still provide for the aspiration of a wash liquid slug Wof suitable volume.

Considering now the effect of the pulsation 104 which occurs as setforth hereinabove as a pump roller discontinues the occlusion of thecompressible pump tube 36, it may be understood that this point in theoperation of the compressible tube pump 10 is illustrated in FIG. 2wherein the pump roller 50A is depicted as discontinuing occludingcontact with said pump tube. Travel of the resultant pulsation 104 inthe upstream direction through the sample portion stream S will besubstantially terminated at the pump roller 508 which is, at this pointin time, occluding the compressible pump tube 36. Travel of thispulsation in the downstream direction through said sample portion streamto and through the T-fitting wherein said stream is being merged withthe stream of reagent liquid R from reagent liquid supply conduit 88will, however, occur, to thus give rise to the possibility of impropersample portion-reagent liquid proportioning. This is to say that if saidpulsation arrives at said T-fltting concomitantly with a sample portionand a segment R of reagent liquid, the attendant momentary reduction inthe sample portion stream flow rate will, of course, result in themerger therewith of a substantially greater proportion of reagent liquidthan that desired with attendant inordinate dilution of said sampleportion. To prevent this from occurring or, to at least minimize theeffects thereof upon sample portion analysis as discussed in greaterdetail hereinbelow, it may be understood that the length of the fluidflow path through the compressible pump tube 36 from the point thereonwhereat the respective pump rollers discontinue occluding contacttherewith as illustrated by the position of pump roller 50A in FIG. 1,and the T-fitting 90, is precisely predetermined in accordance with thefluid flow rate therethrough to insure that the arrival of the pulsation104 at the said T-llitting will occur substantially concomitantly withthe arrival of an air segment A1 or A2 thereat. As a result, it may beunderstood that disruptive effects, if any, of the pulsation 104 uponthe requisite substantially precise sample portion-reagent liquidproportioning will be minimized and will, in any event, occur at thebeginning or end of each of said sample portions so as not to interferewith the results of the analysis thereof.

More specificallyand bearing in mind that the nonillustrated sampletreatment and analysis means of the type discussed include colorimetermeans through which the appropriately treated sample portions which thenconstitute the sample portion stream S are successively flowed, andoperatively connected null balance-type strip chart recorder means whichprovide a record of the colorimetric analysis of said sample portion,all as described in detail in said US. Pat. No. 3,241,432-FIG. 4 whichdepicts a graph 106 of treated sample portion optical density plottedagainst time for the successive passage of three treated sample portionsthrough the colorimeter flow cell is believed to make clear that it isonly the result of the colorimetric quantitative analysis of therespective generally central parts of said treated sample portions whichare recorded to thereby make clear that any nonrepresentative changes insample portion optical density which might occur as a result of impropersample portion-reagent liquid proportioning at the beginning or end ofeach sample portion will have no effect upon the recorded results ofinterest.

Although disclosed in FIGS. 1 and 2 as functioning to aspirate a segmentof air A, a segment of wash liquid W and a segment of air A,respectively, prior to the aspiration of each of the sample portionsfrom the respective sample containers 16, it is believed clear that thesample portion supply means 12 could be modified by the deletion of thewash liquid reservoir 24 and the arrangement of the sample offtake means18 to aspirate repeated small volumes of each of the samples as spaced,each from the other, by a small segment of air A, prior to theaspiration of the main body of the sample portion-with said small sampleportion volumes functioning in the manner of the wash liquid inconjunction with said air segments as the separating fluid portion toremove the residue, if any, of the preceding sample portion and inhibitthe contamination of the succeeding sample portion therebyand that theteachings of the invention should be equally applicable to such system.More specifically, and as seen in FIG. which illustrates the sampleportion stream which would result from such operation, it may beunderstood that the respective turntable 14, sample offtake tubes 20,proportioning pump and T-lfitting 90 would respectively again bearranged as described in detail hereinabove to insure that the offtaketube inlet end would be immersed in a sample container concomitantlywith the arrival thereat of the pulsation 102 for each of the pumprollers 50, and to insure that the arrival of the pulsation 104 for eachof the pump rollers at the T-fitting 90 would occur substantiallyconcomitantly with the arrival of one of said air segments A thereat.

Preferably, the apparatus of the invention are arranged as illustratedand described so that each of the pump rollers makes occluding contactwith the compressible pump tube 36 generally intermediate a sampleportion as shown as at S1, S2, S3, etc., rather than at a separatingfluid portion, to thus prevent the breaking up of the respective airsegments A by such occluding contact into air bubbles which may notreform as air segments and thus would no longer function to occlude thecompressible pump tube 36 to very significant disadvantage as discussedin detail hereinabove.

T00, and although disclosed as involving one pump tube occluding contactby a pump roller per sample portion, it is believed clear that theproportioning pump 10 may alternatively be arranged to operate with onesuch pump tube occluding contact per two or more sample portions to, inany event, minimize the number of pump roller-compressible pump tubecontacts per sample portion and thus minimize compressible pump tubewear as should be obvious.

in addition, and although disclosed by way of illustration as applied toa sample supply system which operates to supply blood serum samples formixture with a suitable color-producing reagent liquid, it is believedclear that the teachings of this invention would be equally applicableto sample supply systems which operate to supply a wide variety ofdifferent sample treatment fluids. Further, and although disclosed inconjunction with a sample supply system which utilizes a compressibletube or peristaltic proportioning pump, it may be understood that theteachings of this invention would be equally applicable to such systemwherein it utilized another and different form of pumping means whichgave rise to pulsations in the nature of those discussed.

While we have shown and described the preferred embodiment of ourinvention, it will be understood that the invention may be embodiedotherwise than as herein specifically illustrated or described, and thatcertain changes in the form and arrangement of parts and in the specificmanner of practicing the invention may be made without departing fromthe underlying idca or principles of this invention within the scope ofthe appended claims.

What is claimed is:

1. In a method for minimizing the effects of pulsations in anintennittent pumping system having a pump which operates by thealternating intake through pump inlet means of sample fluid andseparating fluid, respectively, to provide a fluid stream whichcomprises a series of sample fluid portions spaced by separating fluidportions, and wherein said pulsations travel in said fluid stream tosaid pump inlet means, the steps of, operating said pumping system toprovide for the intake of said sample fluid through said pump inletmeans substantially concomitantly with the arrival of said pulsations atsaid pump inlet means.

2. In a method as in claim 1 further comprising, the steps of, operatingsaid pumping system to respectively provide for sample fluid portions ofsubstantially the same volume, and to provide for separating fluidportions of substantially the same volume 3. In a method as in claim 1wherein said pump comprises a progressively occludable pump tube andsaid method further comprises, the steps of, operating said pumpingsystem to provide separating fluid portions of the minimum volumerequired to occlude said pump tube.

4. In a method as in claim 2 further comprising, the steps of, operatingsaid pumping system to provide sample fluid portion volumes which aregreater than said separating fluid portion volumes.

5. In a method as in claim 4 wherein said pump comprises a progressivelyoccludable pump tube and said method further comprises, the steps of,operating said pumping system to provide separating fluid portions ofthe minimum volume required to occlude said pump tube.

6. ln a method for minimizing the effects of pulsations in anintermittent pumping system having a pump, the steps of, alternatelyimmersing the pump inlet means in different ones of a plurality offluids which are successively supplied thereto,

and exposing said pump inlet means to the ambient air, respectively, toprovide a fluid stream which comprises a series of difierent fluidportions spaced, in each instance, by a separating fluid portion whichcomprises an air segment, and in which fluid stream said pulsationstravel upstream to said pump inlet means, and operating said pump andsaid pump inlet means to provide for the immersion of said pump inletmeans in a said fluid substantially concomitantly with the arrival ofsaid pulsations at said pump inlet means.

7. In a method as in claim 6 further comprising, the steps of, operatingsaid pump and said pump inlet means to respectively provide for fluidportions of substantially the same volume, and to provide for airsegments of substantially the same volume.

8. In a method as in claim 6 wherein said pump comprises a progressivelyoccludable pump tube and said method further comprises, the steps of,operating said pump and said pump inlet means to provide air segments ofthe minimum volume required to occlude said pump tube.

9. In a method as in claim 7 further comprising, the steps of, operatingsaid pump and said pump inlet means to provide fluid portion volumeswhich are greater than said air segment volumes.

10. In a method as in claim 9 wherein said pump comprises aprogressively occludablepump tube and said method further comprises, thesteps of, operating said pump and said pump inlet means to provide airsegments of the minimum volume required to occlude said pump tube.

11. In a method of minimizing the efiects of pulsations on theproportionate merger of a first fluid and a second fluid at the junctureof the flow path of a first fluid stream which comprises a series offirst fluid portions spaced, in each instance, by a separating fluidportion, with the flow path of a second fluid stream, wherein said firstfluid stream is intermittently pumped by a pumping means to result inthe occurrence of said pulsations which travel in said first fluidstream to said flow path juncture, the steps of, arranging said fluidstream flow paths to provide for the substantially concomitant arrivalof said pulsations and said separating fluid portions at said flow pathjuncture.

12. In a method as in claim 11 wherein, the steps of arranging saidfluid stream flow paths comprise the establishment of the length of saidfirst fluid stream flow path between the outlet side of said pumpingmeans and said flow path juncture in accordance with the flow ratethrough said first fluid stream flow path to provide for saidsubstantially concomitant pulsations and separating fluid portionsarrivals at said flow path juncture.

13. In a method for respectively minimizing the effects of pulsations ona first fluid stream, and on the proportionate merger of said firstfluid stream and a second fluid stream at the juncture of the flow pathsthereof, in an intermittent pumping system having a pump which operatesby the alternating intake through pump inlet means of said first fluidand a separating fluid, respectively, to provide said first fluid streamwhich comprises a series of fluid portions spaced, in each instance, bya separating fluid portion, and wherein said pulsations travel in saidfirst fluid stream to said pump inlet means and said flow pathsjuncture, respectively, the steps of, operating said pumping system toprovide for the intake of said first fluid through said pump inlet meanssubstantially concomitantly with the arrival of said pulsations at saidpump inlet means, and arranging said fluid stream flow paths to providefor the substantially concomitant arrival of said pulsations and saidseparating fluid portions at said flow paths juncture.

14. In a method as in claim 13 further comprising, the steps of,operating said pumping system to respectively provide for fluid portionsof substantially the same volume, and to provide for separating fluidportions of substantially the same volume.

15. In a method as in claim 13 wherein said pump comprises aprogressively occludable pump tube and said method further comprises,the steps of, operating said pumping system to provide separating fluidportions of the minimum volume required to occlude said pump tube.

6. In a method as in claim I4 further comprising, the steps of,operating said pumping system to provide fluid portion volumes which aregreater than said separating fluid portion volumes.

17. In a method as in claim 16 wherein said pump comprises aprogressively occludable pump tube and said method further comprises,the steps of, operating said pumping system to provide separating fluidportions of the minimum volume required to occlude said pumptube.

18. In a method as in claim 15 wherein, the steps of arranging saidfluid stream flow paths comprise the establishment of the length of saidfirst fluid stream flow path between the outlet side of said pumpingmeans and said flow path juncture in accordance with the flow ratethrough said first fluid stream flow path to provide for saidsubstantially concomitant pulsations and separating fluids portionsarrivals at said flow path juncture.

19. In a method as in claim 17 wherein, the steps of arranging saidfluid stream flow paths comprise the establishment of the length of saidfirst fluid stream flow path between the outlet side of said pumpingmeans and said flow path juncture in accordance with the flow ratethrough said first fluid stream flow path to provide for saidsubstantially concomitant pulsations and separating fluid portionsarrivals at said flow path juncture.

20. In a method for respectively minimizing the efi'ects of pulsationson a first fluid stream, and on the proportionate merger of said firstfluid stream and a second fluid stream at the juncture of the flow pathsthereof, in an intermittent pumping system having a pump, the steps of,alternately immersing the pump inlet means in different ones of aplurality of fluids which are successively supplied thereto, andexposing said pump inlet means to the ambient air, respectively, toprovide a first fluid stream which comprises a series of difl'erentfluid portions spaced, in each instance, by a separating fluid portionwhich comprises an air segment, and wherein said pulsations travel insaid first fluid stream to said pump inlet means and to said flow pathsjuncture, respectively, operating said pump and said pump inlet means toprovide for the immersion of said pump inlet means in a said fluidsubstantially concomitantly with the arrival of said pulsations at saidpump inlet means, and arranging said fluid stream flow paths to providefor the substantially concomitant arrival of said pulsations and saidseparating fluid portions at said flow paths juncture.

21. In a method as in claim 20 further comprising, the steps of,operating said pump and said pump inlet means to respectively providefor air segments of substantially the same volume, and to provide forair segments of substantially the same volume.

22. In a method as in claim 20 wherein said pump comprises aprogressively occludable pump tube and said method further comprises,the steps of, operating said pump and said pump inlet means to provideair segments of the minimum volume required to occlude said pump tube.

23. In a method as in claim 21 further comprising, the steps of,operating said pump and said pump inlet means to provide fluid portionvolumes which are greater than said air segment volumes.

24. In a method as in claim 23 wherein said pump comprises aprogressively occludable pump tube and said method further comprises,the steps of, operating said pump and said pump inlet means to provideair segments of the minimum volume required to occlude said pump tube.

25. In a method as in claim 24 wherein, the steps of arranging saidfluid stream flow paths comprise the establishment of the length of saidfirst fluid stream flow path between the outlet side of said pumpingmeans and said flow path juncture in accordance with the flow ratethrough said first fluid stream flow path to provide for saidsubstantially concomitant pulsations and separating fluid portionsarrivals at said flow path juncture.

* 1K i t i

1. In a method for minimizing the effects of pulsations in anintermittent pumping system having a pump which operates by thealternating intake through pump inlet means of sample fluid andseparating fluid, respectively, to provide a fluid stream whichcomprises a series of sample fluid portions spaced by separating fluidportions, and wherein said pulsations travel in said fluid stream tosaid pump inlet means, the steps of, operating said pumping system toprovide for the intake of said sample fluid through said pump inletmeans substantially concomitantly with the arrival of said pulsations atsaid pump inlet means.
 2. In a method as in claim 1 further comprising,the steps of, operating said pumping system to respectively provide forsample fluid portions of substantially the same volume, and to providefor separating fluid portions of substantially the same volume.
 3. In amethod as in claim 1 wherein said pump comprises a progressivelyoccludable pump tube and said method further comprises, the steps of,operating said pumping system to provide separating fluid portions ofthe minimum volume required to occlude said pump tube.
 4. In a method asin claim 2 further comprising, the steps of, operating said pumpingsystem to provide sample fluid portion volumes which are greater thansaid separating fluid portion volumes.
 5. In a method as in claim 4wherein said pump comprises a progressively occludable pump tube andsaid method further comprises, the steps of, operating said pumpingsystem to provide separating fluid portions of the minimum volumerequired to occlude said pump tube.
 6. In a method for minimizing theeffects of pulsations in an intermittent pumping system having a pump,the steps of, alternately immersing the pump inlet means in differentones of a plurality of fluids which are successively supplied thereto,and exposing said pump inlet means to the ambient air, respectively, toprovide a fluid stream which comprises a series of different fluidportions spaced, in each instance, by a separating fluid portion whichcomprises an air segment, and in which fluid stream said pulsationstravel upstream to said pump inlet means, and operating said pump andsaid pump inlet means to provide for the immersion of said pump inletmeans in a said fluid substantially concomitantly with the arrival ofsaid pulsations at said pump inlet means.
 7. In a method as in claim 6further comprising, the steps of, operating said pump and said pumpinlet means to respectively provide for fluid portions of substantiallythe same volume, and to provide for air segments of substantially thesame volume.
 8. In a method as in claim 6 wherein said pump comprises aprogressively occludable pump tube and said method further comprises,the steps of, operating said pump and said pump inlet means to provideair segments of the minimum volume required to occlude said pump tube.9. In a method as in claim 7 further comprising, the steps of, operatingsaid pump and said pump inlet means to provide fluid portion volumeswhich are greater than said air segment volumes.
 10. In a method as inclaim 9 wherein said pump comprises a progressively occludable pump tubeand said method further comprises, the steps of, operating said pump andsaid pump inlet means to provide air segments of the minimum volumerequired to occlude said pump tube.
 11. In a method of minimizing theeffects of pulsations on the proportionate merger of a first fluid and asecond fluid at the juncture of the flow path of a first fluid streamwhich comprises a series of first fluid portions spaced, in eachinstance, by a separating fluid portion, with the flow path of a secondfluid stream, wherein said first fluid stream is intermittently pumpedby a pumping means to result in the occurrence of said pulsations whichtravel in said first fluid stream to said flow path juncture, the stepsof, arranging said fluid stream flow paths to provide for thesubstantially concomitant arrival of said pulsations and said separatingfluid portions at said flow path juncture.
 12. In a method as in claim11 wherein, the steps of arranging said fluid stream flow paths comprisethe establishment of the length of said first fluid stream flow pathbetween the outlet side of said pumping means and said flow pathjuncture in accordance with the flow rate through said first fluidstream flow path to provide for said substantially concomitantpulsations and separating fluid portions arrivals at said flow pathjuncture.
 13. In a method for respectively minimizing the effects ofpulsations on a first fluid stream, and on the proportionate merger ofsaid first fluid stream and a second fluid stream at the juncture of theflow paths thereof, in an intermittent pumping system having a pumpwhich operates by the alternating intake through pump inlet means ofsaid first fluid and a separating fluid, respectively, to provide saidfirst fluid stream which comprises a series of fluid portions spaced, ineach instance, by a separating fluid portion, and wherein saidpulsations travel in said first fluid stream to said pump inlet meansand said flow paths juncture, respectively, the steps of, operating saidpumping system to provide for the intake of said first fluid throughsaid pump inlet means substantially concomitantly with the arrival ofsaid pulsations at said pump inlet means, and arranging said fluidstream flow paths to provide for the substantially concomitant arrivalof said pulsations and said separating fluid portions at said flow pathsjuncture.
 14. In a method as in claim 13 further comprising, the stepsof, operating said pumping system to respectively provide for fluidportions of substantially the same volume, and to provide for separatingfluid portions of substantially the same volume.
 15. In a method as inclaim 13 wherein said pump comprises a progressively occludable pumptube and said method further comprises, the steps of, operating saidpumping system to provide separating fluid portions of the minimumvolume required to occlude said pump tube.
 16. In a method as in claim14 further comprising, the steps of, operating said pumping system toprovide fluid portion volumes which are greater than said separatingfluid portion volumes.
 17. In a method as in claim 16 wherein said pumpcomprises a progressively occludable pump tube and said method furthercomprises, the steps of, operating said pumping system to provideseparating fluid portions of the minimum volume required to occlude saidpump tube.
 18. In a method as in claim 15 wherein, the steps ofarranging said fluid stream flow paths comprise the establishment of thelength of said first fluid stream flow path between the outlet side ofsaid pumping means and said flow path juncture in accordance with theflow rate through said first fluid stream flow path to provide for saidsubstantially concomitant pulsations and separating fluids portionsarrivals at said flow path juncture.
 19. In a method as in claim 17wherein, the steps of arranging said fluid stream flow paths comprisethe establishment of the leNgth of said first fluid stream flow pathbetween the outlet side of said pumping means and said flow pathjuncture in accordance with the flow rate through said first fluidstream flow path to provide for said substantially concomitantpulsations and separating fluid portions arrivals at said flow pathjuncture.
 20. In a method for respectively minimizing the effects ofpulsations on a first fluid stream, and on the proportionate merger ofsaid first fluid stream and a second fluid stream at the juncture of theflow paths thereof, in an intermittent pumping system having a pump, thesteps of, alternately immersing the pump inlet means in different onesof a plurality of fluids which are successively supplied thereto, andexposing said pump inlet means to the ambient air, respectively, toprovide a first fluid stream which comprises a series of different fluidportions spaced, in each instance, by a separating fluid portion whichcomprises an air segment, and wherein said pulsations travel in saidfirst fluid stream to said pump inlet means and to said flow pathsjuncture, respectively, operating said pump and said pump inlet means toprovide for the immersion of said pump inlet means in a said fluidsubstantially concomitantly with the arrival of said pulsations at saidpump inlet means, and arranging said fluid stream flow paths to providefor the substantially concomitant arrival of said pulsations and saidseparating fluid portions at said flow paths juncture.
 21. In a methodas in claim 20 further comprising, the steps of, operating said pump andsaid pump inlet means to respectively provide for air segments ofsubstantially the same volume, and to provide for air segments ofsubstantially the same volume.
 22. In a method as in claim 20 whereinsaid pump comprises a progressively occludable pump tube and said methodfurther comprises, the steps of, operating said pump and said pump inletmeans to provide air segments of the minimum volume required to occludesaid pump tube.
 23. In a method as in claim 21 further comprising, thesteps of, operating said pump and said pump inlet means to provide fluidportion volumes which are greater than said air segment volumes.
 24. Ina method as in claim 23 wherein said pump comprises a progressivelyoccludable pump tube and said method further comprises, the steps of,operating said pump and said pump inlet means to provide air segments ofthe minimum volume required to occlude said pump tube.
 25. In a methodas in claim 24 wherein, the steps of arranging said fluid stream flowpaths comprise the establishment of the length of said first fluidstream flow path between the outlet side of said pumping means and saidflow path juncture in accordance with the flow rate through said firstfluid stream flow path to provide for said substantially concomitantpulsations and separating fluid portions arrivals at said flow pathjuncture.